Discovering DNA in Dirt, & 4 Other Amazing Things that Happened in Paleoanthropology Last Week!

Did you blink at any point in the last week? If so, you may have missed some incredible paleoanthropology announcements. This exciting branch of science is out to remind us, once again, that big things are unfolding–and a blink or a short doze might mean you miss another exciting news story. Because so much happened in the last week, I’ve written a short roundup of my favorites. In past posts, I’ve put together lists of the most interesting paleoanthropology of the year, even of the month, but I have never felt the need to round up multiple amazing developments that came out in a single week. So, to help cope with my overwhelming excitement, I compiled a countdown of my favorite announcements from last week (though please remember, as is always the case in science, these studies are new and may be modified or overturned as they are further tested!):

Australopithecus sedibaImage: Professor Berger/Wits University

5. Australopithecus sediba‘s place in the family tree. When sediba was first announced, the species was hypothesized to possibly be ancestral to some branch of the genus Homo. A new study, however, challenges this notion, suggesting that many of the features that appear “homo-like” are actually the result of the fossil being that of a juvenile–approximately the age of a 7th grader. While this questioning of sediba’s place in the family tree is not new, this study is interesting because it takes a closer look at how traits develop in Australopiths. As always, to ultimately settle the debate, more fossils (especially fossils of adults!) would help.

4. The age of Homo naledi. When the strange hominins known as Homo naledi were announced in 2015, a persistent question many people had was: how long ago did they live? Since their discovery, scientists in South Africa have been working to answer that question. In a strange turn of events last week (in the already unique naledi story) National Geographic seems to have broken the news that naledi was far younger than some scientists expected. They lived approximately 200,000 years ago, which is fascinating because they maintained many primitive features and had tiny, tiny brains. Because this appears to be a leak, we don’t yet have the paper with information on how the bones were dated etc, but stay tuned.

Homo naledi

3. Homo floresiensis not descended from Homo erectus? Where did the tiny hobbits on found on the Indonesian island of Flores come from? Who were their closest relatives? These have been big questions in the study of floresiensis over the past decade, and one plausible hypothesis was that they were simply a dwarfed version of a hominin we know was in the area: Asian Homo erectus. Now, a new study refutes that idea, suggesting instead that the hobbits descended from a hominin more primitive than erectus. But if not erectus, then who? We don’t know, maybe a creature more similar to Homo habilis. What’s impressive about this study is it’s extraordinarily comprehensive, the researchers examined 133 cranial, skeletal, and dental samples from a variety of ancient and modern species for comparison throughout Asia, Africa, and Europe.

2. Homo naledi could speak. Just before news broke of the naledi date, another study surfaced that examined the brain of these interesting hominins. Scientists looked at the endocast, the imprint of the brain on the skull, to try to learn more about which parts were developed and which weren’t. Their findings? Though the brain is small, it is organized in an advanced manner, much like modern humans. Most surprisingly, naledi may have had the ability to speak, suggested by the development of a certain part of the frontal lobe. A crazy thing to think about!

A virtual endocast of Naledi’s brain. Image: Heather Garvin

1. Ancient Hominin DNA in cave sediments. Not too long ago, no one knew if DNA could survive after an organism died. Then, the field of ancient DNA was born and scientists began to recover and interpret DNA from long dead creatures like Neanderthals. Now, the field has taken yet another giant leap forward, recovering DNA not from the bones themselves, but from random dirt left behind. Scientists announced last week that they were able to find and identify genetic traces of both Neandertals and Denisovans in cave sediment, likely the result of these hominins once defecating or otherwise leaving behind their genetic mark. Let me repeat the craziest part of this: they discovered DNA without discovering bones. We can now learn that Neanderthals visited particular caves even if we don’t find their bones or stone tools. “It’s a bit like discovering that you can extract gold dust from the air,” population geneticist Adam Siepel commented–a sentiment that captures the incredible nature of this find. This will likely lead to further interesting discoveries, for example, as Chris Stringer pointed out, the technique could reveal the existence of other ancient hominin species–ones we don’t even know about yet!

Bonus: A questionable North American archaeological site. Another bomb that was dropped last week was the claim of evidence of human presence in California 130,000 years ago. If proven to be correct, this would be huge because it pushes back the date of when humans arrived in North America by over 100,000 years. Many scientists have found the evidence lacking, however, because it is simply based on broken rocks found near mastodon bones.The term that has been used often with this announcement, is that extraordinary claims require extraordinary evidence, and many scientists do not see this evidence as extraordinary. Nonetheless, I think this type of mind-bending hypothesis raises interesting questions. For example, if this were true, were these butcherers even human? Theoretically, they could have been Denisovans, Neanderthals, or some creature yet to be discovered! It’s fun to think about.

All this in one week! Are you guys and gals as exhausted as I am?! Seriously though, cheers to an exciting area of science, and thank you to all the incredible people who are working to make these discoveries and further our knowledge about ourselves and our origins. The amount of work that goes into finding, examining, and understanding these fossils is truly massive. Did I miss anything?! Let me know in the comments!